1. Field of the Invention
This invention relates to a method of depositing a metal on a surface and more particularly, to a method of selectively depositing an electroless metal deposit on a surface.
2.Discussion of the Prior Art
Heretofore, it has been known to employ a number of pretreatment or sensitization baths in effecting the electroless deposition of metals on various surfaces. Typically, such prior art sensitization baths used commercially have been expensive because they depend upon a noble metal, e.g., Pd, Pt, Ag, Au, etc., as the sensitizing component. However, recently methods have been reported in which electroless metal deposits can be applied to a broad variety of insulating substrates without the need to use expensive nobel metals but on the contrary, employ reducible salt compositions of non-noble metals. U.S. Pat. Nos. 3,772,056; 3,772,078; 3,907,621; 3,925,578; and 3,930,963 disclose such methods. A problem with the methods disclosed in these patents and not recognized or addressed thereby or therein is that of moisture or humidity which affects a catalytic real image formed by the methods and the resultant electroless metal deposit.
U.S. Pat. No. 3,859,092 discloses metallizing a latent image, formed by actinic radiation exposure of a copper (I) complex or coordination compound by treating the latent image with a chemical developer containing a reducing agent for ions contained in the latent image. However, it has not heretofore been know how to fix or stabilize the real image, produced by the methods of the patents referred to in the preceding paragraph, in the presence of non-noble metal ions which are not bound up, as by being complexed or coordinated. Accordingly, a method of fixing or stabilizing the real image is needed and is an object of this invention.